Flutterby: Morphing for a mate

Q.What is the purpose of butterflies? I ask because my sister gave me a new shower curtain decorated with dozens of them, making me wonder if they're here on Earth for us to look at something very beautiful and not just a million ugly bugs?" –C. C. San

A. Ugly bugs? Just remember that the next worm-like, green, hairy, multi-legged "ugly bug" you spot on one of your yard plants may actually be that very same beautiful butterfly you see there the following month, says Kenneth Bliss of The Lepidopterists' Society. Butterflies (and moths) are merely the adult form of caterpillars, waving their gorgeous wings to attract a mate. That they attract us, too, is merely a pleasurable gift.

But the brightly colored wings attract birds and other predators as well. To deter these, some butterflies have adapted to look like "distasteful" butterflies, such as the Viceroy resembling the Monarch.

"Some also sport natural danger colors like red or yellow, pretty to us and other butterflies, but a turn-off to a bird in search of a meal."

Q.Demographers say a few people alive today could be around to witness an amazing world statistical reversal, the first time this will occur since the dawn of civilization 10,000 years ago. What is this pivotal population event? –J. Kevorkian

A. The United Nations predicts that the "global crude death rate" will start rising, says New Scientist magazine. This rate measures the number of people per 1000 who die in a year, which has dropped from about 40 in pre-agricultural societies to around 8.7 today. You would think a newly rising figure would be bad, but it will reflect that the world's population is aging, thanks to improved health care. At first in developing nations, the crude death rate drops as life expectancy rises; but then as millions whose lives were saved as infants reach old age and start dying in droves, the crude death rate rises again.

"This transition has already occurred in many developed countries and is now set to happen on a global scale," the article says. As the world's crude death rate overtakes the crude birth rate, says New Scientist, global population growth will halt and population will fall, having reached the high-water mark.

The expected year for this? 2075, says the U.N., with both birth and death rates standing at 11.4 and the world topping out at 9.22 billion people!

Q.Some 100 muscles take part in it, your elbow needing to know what your shoulder is doing, your shoulder gauging your body's trunk riding at the speed of your legs. Each time you must synchronize the flow of fingers, wrist, elbow, shoulder, torso, and execute it in about 1/8th second to hit your target. And a variable target at that, now a little higher or lower, or more to the left or right, or moving at a different speed. Chimps can't do this well but humans can, something our ancestors refined over a thousand millennia. What are you doing? W. Ford

A. Accurate throwing, as described by neurobiologist William H. Calvin in A Brief History of the Mind. This is not just flinging– which many chimps do– but practicing to hit smaller and smaller targets. Nor is it like a dart throw or basketball free throw, where the idea is to perform the action the same way over and over. Think rather of a baseball throw, the outfielder turning and wheeling to try to hit the catcher 350 feet away to stop the critical run from scoring. Cheers go up, though not many in the stands stop to think the play was a million years in the making!